Smart cards with a security controller are used for example for security-relevant applications. Such smart cards can be used for access authorization proofs, bank cards or pay television access cards. Often their use is provided only for a predetermined period of time or is intended to be prevented after issue, for example when the access authorization is cancelled or the pay television contract is terminated. The withdrawal of such cards by the issuer is associated with high effort and costs, or is not possible. Therefore, these cards usually have a predetermined validity, after the expiry of which their operation is intended to be prevented. After the validity has expired, these cards remain in circulation, and there is the risk that these cards can be reprogrammed and converted to another purpose or be used for illegal purposes by experienced attackers.
Various approaches have been pursued hitherto in order to block the cards as far as possible permanently after their validity has expired. By way of example, a protection by so-called “fuses” which is programmed and implemented in hardware can be provided, which prevents access after the validity has expired. Since this is tested prior to every use, a further use of the security controller can thus be impeded after the validity has expired.
According to different approaches values are written to one or more memory cells, which values are then checked by the program or the hardware of the security controller and, if appropriate, trigger the blocking of the further program sequence.
Furthermore the programming voltage of a chip is blocked, such that the latter can no longer be reprogrammed as easily.